The Invisible Danger
Crude glycerin isn't just dirty soap; it's a hazardous chemical soup. The primary danger lies in the invisible Methanol content, which is highly flammable and toxic, mixed with caustic catalysts.
The pH Rollercoaster
Purification is a game of chemical seesaw. We must swing the mixture from highly caustic to acidic to break the soaps, then back to neutral for safety.
WARNING: Exothermic reactions occur during acid addition.
The Purification Timeline
Turning toxic sludge into technical-grade product takes time, not just chemistry. Patience prevents explosions.
Phase 1: Settling
Gravity does the first pass. Allow the mix to sit in a sealed HDPE container. The heavy glycerin sinks; biodiesel floats. Drain the bottom layer carefully.
Phase 2: Demethylation
The most critical step. Methanol must be removed via passive evaporation (outdoors) or careful heating. This breaks the fire triangle.
Phase 3: Acidulation
Add Phosphoric or Sulfuric acid to drop pH to ~3.5. This splits the soaps into Free Fatty Acids (FFA), which float to the top for removal.
Phase 4: Neutralization
Bring pH back to 7.0 using a catalyst solution. Salt precipitates out. Filter or settle to reveal amber Technical Grade Glycerin.
Result Analysis
Comparing the raw byproduct to the refined output.
Critical Risk Factors
Ignites at room temperature.
Causes severe skin burns.
Skin absorption risk.
Illegal to dump in soil.